The present invention relates to a grapple unit and more particularly to such a unit arranged upon one end of a logging machine for securing logs and the like of varying sizes.
It is well known to provide logging vehicles or skidders with a grapple unit at one end for securing trees or logs which are to be moved by the vehicle. Since the vehicle may be employed to move very large trees or even a number of trees at one time, it is necessary to design the grapple unit for continued operation under very substantial stresses. Also, in order to assure reliable and continued operation, it is necessary to prevent the grapple unit from being damaged by engagement with the logs it is intended to engage.
A skidder vehicle of the type contemplated by the present invention may be used primarily for conveying felled trees to a mill or other processing site. On the other hand, the trees may be delimbed and cut into logs of selected length or otherwised processed prior to being moved by the skidder vehicle. Since the skidder vehicles operate under widely varying conditions and commonly encounter rough terrain, it is necessary to insure that logs or trees of varying sizes be firmly secured by the grapple unit during conveyance by the skidder vehicle.